Today, parasite airplanes. The University of Houston's College of Engineering
presents this series about the machines that make our civilization
run, and the people whose ingenuity created them.

Nobody blinks when they see a small boat being carried
by a large one -- lifeboats, whaleboats, dinghies. And we often see Rec-Vecs
towing small automobiles. But an airplane riding in another airplane -- well
somehow that's another matter. Yet such hitchhikers are a tradition as old as
the airplane itself. They're call parasites. When airplanes first appeared, we
already had dirigibles. People immediately imagined those great whales in the
sky carrying little lifeboat airplanes.

But the first parasite airplane did not ride on a dirigible. Rather, the British
put a Bristol Scout
on the upper wing of a huge biplane bomber,
built for the express purpose of carrying it. That system was tried once, in 1916,
then abandoned. Two years later, the British did use their 23R Dirigible to carry a
Sopwith Camel
pursuit plane. It dangled below the 535-foot monster. The dirigible released one
of those airplanes on three occasions. The system seemed to work, but it was clumsy.
And it was never put to any use.

Between wars, Curtiss built his Sparrowhawk, a parasite airplane for the US Navy.
It was a small biplane that flew from the US dirigible
Macon. Its landing gear
could be removed if it were meant to return to roost in the dirigible's pick-up sling.
And yet the pretty little Sparrowhawk never served as much more than disposable ballast.
Anyway, the Macon soon perished in a crash

I recently visited the Strategic Air Command Museum
outside of Omaha where I gained
some clue as to how this compelling idea refused to give up. There, in the shadow of
the monster B-36 Bomber that once carried it, I found myself
staring at the strangest airplane I'd ever seen. The McDonnell Goblin was a stumpy
little jet fighter with no landing gear.

The Mcdonnell XF-85 Goblin at the Strategic Air and Space Museum in Nebraska. Notice a bit of the
wing and fuselage of the B-36 Bomber behind it. (photo by John Lienhard)

The ten-engine, 230-foot wingspan B-36 could carry
threeGoblins. Yet this idea joined the others on
the scrap heap of dreams. Returning to the mother ship was too tricky. What's more,
that strange, specialized airplane performed rather badly.

We tried other parasite schemes with our big bombers. Then
air-to-air refueling became
practical. It gave fighter support the range it needed. So that strange Goblin jet
was a last gasp of an idea that seemed as though it really ought to work.

Of course, if any idea can be made to work, engineers will make
it work. It can be only a matter of time before someone finds the right configuration
of engineering design and human need. Maybe it will be escape pods for our space vehicles.
By the way, when the Shuttle rides on a 747, that's not a true parasite; it's just cargo.
The Shuttle cannot fly off on its own.

Maybe we doomed this idea when we gave it such a nasty name. Parasites indeed!
Let's call them pet airplanes or maybe aerial children. Maybe that will
be the way we'll finally make this strange idea work.

I'm John Lienhard at the University of Houston,
where we're interested in the way inventive minds
work.